We are going to add an AppStateManager to the project. Let's begin by making the object and then write the component script:

1. In the root of the Hierarchy, create an empty game object, and name it AppStateManager.

2. In the Scripts folder create a new C# script named AppStateManager and drag it onto AppStateManager as a component.

Open the AppStateManager script for editing, as follows:

File: AppStateManager.cs

First, we'll declare the appState and a large set of public variables that will be explained as we use them:

using UnityEngine; 
using UnityEngine.Events; 
using UnityEngine.UI; 
using Vuforia; 
 
public class AppStateManager : MonoBehaviour { 
 
    private AppStates appState; 
    //Vuforia scripts that are used to get the state of the app. Can be found using FindObjectOfType<T>(); 
    public ReconstructionBehaviour reconstructionBehaviour; 
    public SurfaceBehaviour surfaceBehaviour; 
    public ImageTrackableEventHandler imageTarget; 
 
    ///UI 
    public GameObject instructionHolder; 
    public Text instructionsText; 
    public Button doneButton; 
    public Button resetButton; 
 
    //For the game 
    public UnityEvent OnStartGame; 
 
    //UI resources for instructions 
    public string pointDeviceText; 
    public string pullBackText; 
 
} 

The Start() function will register a listener for when tracking is first detected and set our state to INIT_ANIMATION:

    void Start() { 
        imageTarget.OnImageTrackableFoundFirstTime.AddListener( OnImageTrackableFoundFirstTime); 
    } 
 
    private void OnImageTrackableFoundFirstTime() { 
        appState = AppStates.INIT_ANIMATION; 
    } 

The bulk of our state management is performed in Update(). The update action depends on the current state, where we use a big switch statement. This code directly follows the state definitions specified earlier in this section's User experience and app states topic. Begin writing the Update as follows:

    void Update() { 
        //We declare the bool values here because we want them to be set to false, unless the state is correct 
        //This saves us from setting the values to false in each state. 
        bool showDoneButton = false; 
        bool showResetButton = false; 

Now, we begin the big switch statement:

        switch (appState) { 
            //Detection phase 
            case AppStates.OVERLAY_OUTLINE: 
                instructionsText.text = pointDeviceText; 
                surfaceBehaviour.GetComponent<Renderer>().enabled = false; 
                break; 
 
            // The animation that is played when the trackable is found for the first time 
            case AppStates.INIT_ANIMATION: 
                appState = AppStates.SCANNING; 
                break; 
 
            // Scanning phase 
            case AppStates.SCANNING: 
                ShowWireFrame(true); 
                instructionsText.text = pullBackText; 
                showDoneButton = true; 
                break; 
 
            // When the user taps done. This happens before the game can be played 
            case AppStates.GAME_RENDERING: 
                if ((reconstructionBehaviour != null) && (reconstructionBehaviour.Reconstruction != null)) { 
                    ShowWireFrame(false); 
                    surfaceBehaviour.GetComponent<Renderer>().enabled = false; 
                    imageTarget.ToggleOnStateChange = true; 
                    reconstructionBehaviour.Reconstruction.Stop(); 
                    OnStartGame.Invoke(); 
                    appState = AppStates.GAME_PLAY; 
                } 
                break; 
 
            //This is where the user can shoot the ball 
            case AppStates.GAME_PLAY: 
                instructionHolder.gameObject.SetActive(false); 
                showResetButton = true; 
                break; 
 
            //User taps on [RESET] button - Re-loads the level 
            case AppStates.RESET_ALL: 
                //Reloads this scene 
                UnityEngine.SceneManagement.SceneManager.LoadScene(0); 
                appState = AppStates.NONE; 
                break; 
 
            // Just a placeholder state, to make sure that the previous state runs for just one frame. 
            case AppStates.NONE: break; 
        } 

After the switch statement, we include logic to decide when to display the done or cancel buttons, as follows:

        if (doneButton != null && 
            showDoneButton != doneButton.enabled) { 
            doneButton.enabled = showDoneButton; 
            doneButton.image.enabled = showDoneButton; 
            doneButton.gameObject.SetActive(showDoneButton); 
        } 
 
        if (resetButton != null && 
            showResetButton != resetButton.enabled) { 
            resetButton.enabled = showResetButton; 
            resetButton.image.enabled = showResetButton; 
            resetButton.gameObject.SetActive(showResetButton); 
        } 
    } 

That's the end if the Update function. It calls some helper functions as defined next, as follows:

    void ShowWireFrame(bool show) { 
        WireframeBehaviour[] wireframeBehaviours = FindObjectsOfType<WireframeBehaviour>(); 
        foreach (WireframeBehaviour wireframeBehaviour in wireframeBehaviours) { 
            wireframeBehaviour.ShowLines = show; 
        } 
    } 
 
    //Called by the buttons 
    public void TerrainDone() { 
        appState = AppStates.GAME_RENDERING; 
    } 
 
    public void ResetAll() { 
        appState = AppStates.RESET_ALL; 
    } 

I know this is a lot of code and I hope you don't mind following it, let alone typing it into your own app, but when you break it down, each section is just a few lines of code.